In U.S. Pat. No. 4,705,967 by the same inventor of the instant invention, and incorporated herein by reference, it was disclosed that a FET transistor circuit may be used for balanced circuit configurations such as push-pull amplifiers. Such FET transistor is usually fabricated from gallium arsenide (GaAs) and formed with a metal-semiconductor junction, and referred to as a MESFET. With such a MESFET, the source and drain regions become interchangeable. As was disclosed therein, a graph of the current passing between the source and drain regions shows both positive and negative current flows upon a reversal of excitation voltage and, furthermore, shows that the positive and negative portions of the current to be symmetrical. Thus, reversal of the polarity of the excitation voltage, applied between the source and the drain regions, effectively interchanges the source and drain regions. The dependency of the current on gate-source voltage is the same for both positive and negative current flow.
In the '967 patent, by connecting a balun, preferably in the form of a transformer, at the output of the MESFET transistor, two-way transmission of signals, either from the transistor to the unbalanced terminal, or from the unbalanced terminal to a transistor, is achieved, thereby effecting a balanced configuration. Although the circuit of the '967 patent works well for balanced circuits, it was found that for other circuits such as switches, mixers, power amplifiers and modulators where enhanced performance is required, a different type of circuit is needed.